The ultimate goal of this project is to describe a molecular mechanism for te way in which insulin activates membrane transport processes. Insulin causes a rapid stimulation of hexose transport in the target muscle and adipose tissues. The onset of this effect is mediated by the specific interaction of insulin with its cell surface receptor. Recent developments in receptor methodology have allowed the description of a minimum insulin receptor subunit structure. However, the molecular events subsequent to hormone-receptor interaction which lead to the generationof an intracellular signal(s) and the nature of this signal remain unknown. Moreover, very few biochemical details of te insulin-sensitive hexose transport system have been described. It is the specific aim of this proposal to identify, purify and characterize the insulin activated hexose transport system of the rat adipocyte. Metabolic and chemical labeling techniques will be employed to identify the hexose carrier as it is exposed on the plasma membrane surface due to insulin's action. Reconstitution procedures will be employed to monitor hexose transport activity through a variety of purification steps. The purified hexose transporter will be examined for biochemical differences (e.g. phosphorylation, glycosylation) between basal and insulin-activated states. These differences may give clues as to the nature of te signal generated by insulin-receptor interaction. Anti-transporter antibody will be prepared and used as an additional probe for detecting biochemical alterations in the transporter due to insulin as well as possible changes in the transporter in physiologically interesting states such as obesity.